1. Field of the Invention
This invention relates generally to circuit breakers and, more particularly, to circuit breakers of the electromagnetic type including an operating mechanism and an operating handle.
2. Background Information
Circuit breakers of the electromagnetic type are shown, for example, in U.S. Pat. Nos. 3,329,913; and 4,151,386.
Such electromagnetic circuit breakers typically comprise a movable contact, which is mounted on a movable arm, and a fixed or stationary contact. An operating handle is coupled to the movable arm via a linkage mechanism, part of which comprises a collapsible toggle assembly having a first or catch link and a second or U-link. An internal extension of the operating handle is directly pivotally connected to the catch link. The movable and stationary contacts are operated between contacts xe2x80x9copenxe2x80x9d and contacts xe2x80x9cclosedxe2x80x9d positions by pivoting the operating handle. The circuit breaker further comprises an electromagnetic device which, in response to one or more predetermined electrical conditions, collapses the toggle assembly to a broken state, in order to electrically trip xe2x80x9copenxe2x80x9d the separable movable and stationary contacts.
During on and off operation, the operating mechanism employs a rigid linkage mechanism, including the first and second links, to the operating handle. The first end of the second link is pivotally mounted to the second end of the first link and the second end of the second link is pivotally mounted to the movable arm. This provides an early (i.e., relative to handle throw) toggle-on point. At the point where the operating mechanism toggles and the unbroken linkage mechanism begins to move, there is very little energy stored in the operating mechanism springs. As a result, the circuit breaker can be xe2x80x9cteasedxe2x80x9d on, which causes undesirable and potentially damaging arcing to the separable contacts.
xe2x80x9cSlow makexe2x80x9d is defined as the closing velocity of the circuit breaker separable contacts being directly dependent upon the closing. speed of the operating handle. For a circuit breaker operating at relatively high voltages (e.g., 480 to 600 VAC), this results in a greater tendency for the separable contacts to weld closed, and significantly reduces the number of switching operations in the operating life of the circuit breaker.
U.S. patent application Ser. No. 10/185,858, filed Jun. 27, 2002, discloses a circuit breaker including a pivot lever having a first arm with a first end adapted for engagement with a movable contact arm, and a second arm having a second end adapted for engagement with an operating handle assembly. The first end of the pivot lever carries a U-shaped hook member pivotally disposed thereon. The hook member has a J-shaped hook, which is adapted for engagement with the movable contact arm, and a J-shaped pivot end, which is pivotally mounted in an opening of the first arm. In order to eliminate the dependency between the movable contact arm and the operating handle assembly, the J-shaped hook initially hooks the movable contact arm. The pivot end of the hook member is inserted into the first or free end of the pivot lever. The pivot lever pivots about a pin and translates the hook member and the movable contact arm movement up to the operating handle assembly. The second or handle end of the pivot lever interacts with a blocking disk of the operating handle assembly, which disk rotates about the same center as the operating handle, but is allowed independent movement.
There is room for improvement in circuit breakers.
These needs and others are met by the present invention, which provides an independent operating handle link in the circuit breaker operating mechanism. In order to achieve a snap close or fast make action, the independent operating handle link pivots at one end at the operating handle and, also, pivots at the other end at the operating mechanism linkage.
One or more extension springs may be connected to the pivot point for the independent operating handle link and the operating mechanism linkage, in order to load up and snap over as the operating handle is moved from the open position toward the closed position of the circuit breaker.
As one aspect of the invention, a circuit breaker comprises: a case including an opening; separable contacts housed within the case; an operating mechanism for opening and closing the separable contacts, the operating mechanism including a first pivot, a first link and a second link, the first link having a first end and a second end, the first link being pivotally mounted to the first pivot at the first end of the first link and being pivotally mounted to the second link at the second end of the first link; an operating handle for operating the operating mechanism, the operating handle including a first portion extending through the opening of the case, a second portion within the case and a second pivot between the first and second portions; and a third link having a first end and a second end, the third link being pivotally mounted to the second pivot at the first end of the third link and being pivotally mounted to the first pivot of the operating mechanism at the second end of the third link.
The operating handle may have an open position and a closed position. The operating mechanism may further include at least one extension spring extending between the second portion of the operating handle and the first pivot, the at least one extension spring being extended as the operating handle moves from the open position toward the closed position thereof, in order to load the first and second links of the operating mechanism.
The second portion of the operating handle may include a pair of elongated arms. The operating mechanism may further include a pair of extension springs extending between the pair of elongated arms of the operating handle and the first pivot, the extension springs being extended as the operating handle moves from the open position toward the closed position thereof, in order to load the first and second links of the operating mechanism.
The third link may be positioned between the elongated arms.
As another aspect of the invention, a circuit breaker comprises: a case including an opening; separable contacts housed within the case; an operating mechanism for opening and closing the separable contacts, the operating mechanism including a first pivot and a linkage pivotally mounted to the first pivot; an operating handle for operating the operating mechanism, the operating handle including a first portion extending through the opening of the case, a second portion within the case and a second pivot between the first and second portions; and a link having a first end and a second end, the link being pivotally mounted to the second pivot of the operating handle at the first end of the link and being pivotally mounted to the first pivot of the operating mechanism at the second end of the link.
The operating handle may have an open position corresponding to the open position of the separable contacts, and a closed position corresponding to the closed position of the separable contacts. The operating mechanism may further include a pair of extension springs extending between the second portion of the operating handle and the first pivot, the extension springs being extended as the operating handle moves from the open position toward the closed position thereof, in order to load the linkage of the operating mechanism.
The link may be formed by a pair of parallel links.
The second portion of the operating handle may include a pair of elongated arms within the case, and the link may be positioned between the elongated arms.